[The electrocardiogram during physical stress and Holter monitoring in the detection of asymptomatic myocardial infarct].
BACKGROUND
In patients with myocardial infarction acute myocardial ischaemia could be manifested by characteristic ischaemic symptoms or noncharacteristic symptoms such as cardiac insufficiency or heart rhythm disturbances. Sometimes myocardial ischaemia is not followed by any symptom. This condition is known as asymptomatic myocardial ischaemia. Asymptomatic myocardial ischaemia usually could be detected by treadmill exercise tolerance test or 24-hour Holter ECG monitoring.


METHODS
We analyzed a group of 58 patients suffering from myocardial infarction with ST segment depression during the treadmill exercise tolerance test. All patients were on Holter 24-hour ECG monitoring. As a criterion of myocardial ischaemia during Holter monitoring ST segment depression of 1 mm and more, lasting 1 minute and more, and 0.08" of J point was accepted.


RESULTS
During the treadmill exercise tolerance test segment depression was not followed by any symptom in 18 (31%) patients. There were no differences in the number of patients with hypertension in the group with symptoms and the group without symptoms. Diabetes mellitus was more frequent in the group with asymptomatic myocardial ischaemia. The average values of maximum ST segment depression and heart rates during treadmill tests were not statistically significant in both groups (with and without symptoms). During daily activities myocardial ischaemia was found in 30 (51%) patients by a 24-hour Holter ECG monitoring. We observed 198 episodes of myocardial ischaemia of which 138 (69.1%) were asymtomatic. The amplitude of ST segment depression and duration of these changes were significantly greater in the group with symptomatic episodes than in the group with asymptomatic episodes of myocardial ischaemia.


CONCLUSIONS
Asymptomatic myocardial ischaemia is an often appearance in patients with myocardial ischaemia. Almost in 25% of persons in whom sudden death occurred obstructive changes in coronary arteries during the autopsy were found. Asymptomatic myocardial ischaemia could be found even an a "completely healthy person" without any complaints. Asymptomatic myocardial ischaemia is usually detected in a "completely healthy person" by casual diagnosis, in patients with stable and non stable angina pectoris, in patients with stenosis of the coronary arteries proved by angiography, and in patients after myocardial infarction. Some authors considered that treadmill exercise tolerance testing is less reliable to discover asymptomatic myocardial ischaemia comparing to the continuous 24-hour Holter ECG monitoring. It is know that in patients with diabetes mellitus neuropathy precedes the onset of symptomatic myocardial ischaemia. Asymptomatic myocardial ischaemia has the same predictive value for prognosis of the disease as symptomatic myocardial ischaemia. In some patients "anginal alarm system" is defective, and perception and conduction of pain sensations are disturbed.


CONCLUSIONS
1. In 31% of patients who suffered from myocardial infarction with ST segment depression during the treadmill testing asymptomatic myocardial ischaemia was found. 2. By Holter monitoring ischaemia ST segment depression during the exertion is observed in 52% of patients. Most of ischaemic episodes were asymptomatic. 3. The amplitude of ST segment depression is significantly greater and duration of depression is significantly longer in symptomatic episodes of myocardial ischaemia comparing to asymptomatic myocardial ischaemia obtained by Holter ECG monitoring.
Damjanović
M M
MM
Institute of Aviation Medicine of the Yugoslav Army, Belgrade.
D004562:Electrocardiography; D015716:Electrocardiography, Ambulatory; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis*
Elektrokardiogram pri fizickom opterećenju i Holterski monitoring u otkrivanju asimptomske infarkta miokarda.